Described herein are a device (4), a system (1), and a method for the treatment of liquid effluents by means of electric discharges. According to the invention, the electric discharge that is set up in the treatment device following upon application of voltage pulses has characteristics, in terms of amplitude and duration of the pulses, such as not to incur in phenomena of dissipation of energy and such as to emit ultraviolet radiation for further treatment of the effluent.
